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Message-ID: <5f7e3eab-b2d4-3da4-1ef1-07327e17a179@os.amperecomputing.com>
Date: Fri, 22 Apr 2022 11:16:42 +0700
From: Quan Nguyen <quan@...amperecomputing.com>
To: Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
Corey Minyard <minyard@....org>,
Rob Herring <robh+dt@...nel.org>,
Krzysztof Kozlowski <krzysztof.kozlowski@...onical.com>,
Joel Stanley <joel@....id.au>,
Andrew Jeffery <andrew@...id.au>,
Brendan Higgins <brendanhiggins@...gle.com>,
Benjamin Herrenschmidt <benh@...nel.crashing.org>,
Wolfram Sang <wsa@...nel.org>,
openipmi-developer@...ts.sourceforge.net,
devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
linux-aspeed@...ts.ozlabs.org, linux-kernel@...r.kernel.org,
linux-i2c@...r.kernel.org, openbmc@...ts.ozlabs.org
Cc: Open Source Submission <patches@...erecomputing.com>,
Phong Vo <phong@...amperecomputing.com>,
"Thang Q . Nguyen" <thang@...amperecomputing.com>
Subject: Re: [PATCH v7 1/3] ipmi: ssif_bmc: Add SSIF BMC driver
Added Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>
as I'm not aware of the email change
- Quan
On 22/04/2022 11:08, Quan Nguyen wrote:
> The SMBus system interface (SSIF) IPMI BMC driver can be used to perform
> in-band IPMI communication with their host in management (BMC) side.
>
> Thanks Dan for the copy_from_user() fix in the link below.
>
> Link: https://lore.kernel.org/linux-arm-kernel/20220310114119.13736-4-quan@os.amperecomputing.com/
> Signed-off-by: Quan Nguyen <quan@...amperecomputing.com>
> ---
> v7:
> + Remove unneccessary del_timer() in response_timeout() [Corey]
> + Change compatible string from "ampere,ssif-bmc" to "ssif-bmc" [Jae]
> + Add MODULE_DEVICE_TABLE(of, ssif_bmc_match), fix blank line [Jae]
> + Dropped the use of ssif_msg_len() macro, use the len directly [Quan]
> + Solve possible issue if both response timer and ssif_bmc_write()
> occurred at the same time [Corey]
> + Fix wrong return type of ssif_bmc_poll() [kernel robot test]
> + Refactor and introduce ssif_part_buffer struct to replace the
> response_buf to manage each send/receive part of ssif [Quan]
> + Change SSIF_BAD_SMBUS state to SSIF_ABORTING state [Corey]
> + Support abort feature to skip the current bad request/response and
> wait until next new request [Corey]
> + Refactor the PEC calculation to avoid the re-calculate the PEC on
> each I2C_SLAVE_WRITE_RECEIVED event [Quan]
> + Fix the use of error-proned idx [Corey]
> + Defer the test for valid SMBus command until the read/write part
> is determined [Quan]
> + Change/split unsupported_smbus_cmd() to
> supported_[write|read]_cmd() [Corey]
> + Abort the request if somehow its size exceeded 255 bytes [Quan]
>
> v6:
> + Drop the use of slave_enable() [Wolfram]
> + Make i2c-aspeed to issue RxCmdLast command on all
> I2C_SLAVE_WRITE_REQUESTED event to assert NAK when slave busy [Quan]
> + Make i2c slave to return -EBUSY when it's busy [Quan]
> + Drop the aborting feature as return Completion Code 0xFF may stop
> host to retry and make ipmi_ssif.so fails to load [Quan]
> + Add timer to recover slave from busy state when no response [Quan]
> + Clean request/response buffer appropriately [Quan]
> + Add some minor change on error and warning messages [Quan]
>
> v5:
> + None
>
> v4:
> + Send response with Completion code 0xFF when aborting [Quan]
> + Added bounding check on SMBus writes and the whole request [Dan]
> + Moved buffer to end of struct ssif_bmc_ctx to avoid context
> corruption if somehow buffer is written past the end [Dan]
> + Return -EINVAL if userspace buffer too small, dont
> silence truncate [Corey, Joel]
> + Not necessary to check NONBLOCK in lock [Corey]
> + Enforce one user at a time [Joel]
> + Reject write with invalid response length from userspace [Corey]
> + Add state machines for better ssif bmc state handling [Quan]
> + Drop ssif_bmc_aspeed.c and make ssif_bmc.c is generic
> SSIF BMC driver [Quan]
> + Change compatible string "aspeed,ast2500-ssif-bmc" to
> "ampere,ssif-bmc" [Quan]
> + Abort current request with invalid SMBus write or
> invalid command [Quan]
> + Abort all request if there is pending response [Quan]
> + Changed validate_pec() to validate_request() [Quan]
> + Add unsupported_smbus_cmd() to handle unknown SMBus command [Quan]
> + Print internal state string for ease investigating issue [Quan]
> + Move to READY state on SLAVE_STOP event [Quan]
> + Change initilize_transfer() to process_smbus_cmd() [Quan]
> + Introduce functions for each slave event [Quan]
>
> v3:
> + Removed redundant license info [Joel]
> + Switched to use traditional if-else [Joel]
> + Removed unused ssif_bmc_ioctl() [Joel]
> + Made handle_request()/complete_response() to return void [Joel]
> + Refactored send_ssif_bmc_response() and
> receive_ssif_bmc_request() [Corey]
> + Removed mutex [Corey]
> + Use spin_lock/unlock_irqsave/restore in callback [Corey]
> + Removed the unnecessary memset [Corey]
> + Switch to use dev_err() [Corey]
>
> v2:
> + Fixed compiling error with COMPILE_TEST for arc
>
> drivers/char/ipmi/Kconfig | 11 +
> drivers/char/ipmi/Makefile | 1 +
> drivers/char/ipmi/ssif_bmc.c | 780 +++++++++++++++++++++++++++++++++++
> drivers/char/ipmi/ssif_bmc.h | 107 +++++
> 4 files changed, 899 insertions(+)
> create mode 100644 drivers/char/ipmi/ssif_bmc.c
> create mode 100644 drivers/char/ipmi/ssif_bmc.h
>
> diff --git a/drivers/char/ipmi/Kconfig b/drivers/char/ipmi/Kconfig
> index b061e6b513ed..18a89093d64e 100644
> --- a/drivers/char/ipmi/Kconfig
> +++ b/drivers/char/ipmi/Kconfig
> @@ -169,6 +169,17 @@ config ASPEED_BT_IPMI_BMC
> found on Aspeed SOCs (AST2400 and AST2500). The driver
> implements the BMC side of the BT interface.
>
> +config SSIF_IPMI_BMC
> + tristate "SSIF IPMI BMC driver"
> + select I2C
> + select I2C_SLAVE
> + help
> + This enables the IPMI SMBus system interface (SSIF) at the
> + management (BMC) side.
> +
> + The driver implements the BMC side of the SMBus system
> + interface (SSIF).
> +
> config IPMB_DEVICE_INTERFACE
> tristate 'IPMB Interface handler'
> depends on I2C
> diff --git a/drivers/char/ipmi/Makefile b/drivers/char/ipmi/Makefile
> index 7ce790efad92..cb6138b8ded9 100644
> --- a/drivers/char/ipmi/Makefile
> +++ b/drivers/char/ipmi/Makefile
> @@ -30,3 +30,4 @@ obj-$(CONFIG_ASPEED_BT_IPMI_BMC) += bt-bmc.o
> obj-$(CONFIG_ASPEED_KCS_IPMI_BMC) += kcs_bmc_aspeed.o
> obj-$(CONFIG_NPCM7XX_KCS_IPMI_BMC) += kcs_bmc_npcm7xx.o
> obj-$(CONFIG_IPMB_DEVICE_INTERFACE) += ipmb_dev_int.o
> +obj-$(CONFIG_SSIF_IPMI_BMC) += ssif_bmc.o
> diff --git a/drivers/char/ipmi/ssif_bmc.c b/drivers/char/ipmi/ssif_bmc.c
> new file mode 100644
> index 000000000000..4cff5e1a075e
> --- /dev/null
> +++ b/drivers/char/ipmi/ssif_bmc.c
> @@ -0,0 +1,780 @@
> +// SPDX-License-Identifier: GPL-2.0+
> +/*
> + * The driver for BMC side of SSIF interface
> + *
> + * Copyright (c) 2022, Ampere Computing LLC
> + *
> + */
> +
> +#include <linux/i2c.h>
> +#include <linux/miscdevice.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/platform_device.h>
> +#include <linux/poll.h>
> +#include <linux/sched.h>
> +#include <linux/mutex.h>
> +#include <linux/spinlock.h>
> +#include <linux/timer.h>
> +#include <linux/jiffies.h>
> +
> +#include "ssif_bmc.h"
> +
> +static const char *state_to_string(enum ssif_state state)
> +{
> + switch (state) {
> + case SSIF_READY:
> + return "SSIF_READY";
> + case SSIF_START:
> + return "SSIF_START";
> + case SSIF_SMBUS_CMD:
> + return "SSIF_SMBUS_CMD";
> + case SSIF_REQ_RECVING:
> + return "SSIF_REQ_RECVING";
> + case SSIF_RES_SENDING:
> + return "SSIF_RES_SENDING";
> + case SSIF_ABORTING:
> + return "SSIF_ABORTING";
> + default:
> + return "SSIF_STATE_UNKNOWN";
> + }
> +}
> +
> +/* Handle SSIF message that will be sent to user */
> +static ssize_t ssif_bmc_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
> +{
> + struct ssif_bmc_ctx *ssif_bmc = to_ssif_bmc(file);
> + struct ssif_msg msg;
> + unsigned long flags;
> + ssize_t ret;
> +
> + spin_lock_irqsave(&ssif_bmc->lock, flags);
> + while (!ssif_bmc->request_available) {
> + spin_unlock_irqrestore(&ssif_bmc->lock, flags);
> + if (file->f_flags & O_NONBLOCK)
> + return -EAGAIN;
> + ret = wait_event_interruptible(ssif_bmc->wait_queue,
> + ssif_bmc->request_available);
> + if (ret)
> + return ret;
> + spin_lock_irqsave(&ssif_bmc->lock, flags);
> + }
> +
> + if (count < min_t(ssize_t, ssif_bmc->request.len + 1, sizeof(struct ssif_msg))) {
> + spin_unlock_irqrestore(&ssif_bmc->lock, flags);
> + ret = -EINVAL;
> + } else {
> + count = min_t(ssize_t, ssif_bmc->request.len + 1, sizeof(struct ssif_msg));
> + memcpy(&msg, &ssif_bmc->request, count);
> + ssif_bmc->request_available = false;
> + spin_unlock_irqrestore(&ssif_bmc->lock, flags);
> +
> + ret = copy_to_user(buf, &msg, count);
> + }
> +
> + return (ret < 0) ? ret : count;
> +}
> +
> +/* Handle SSIF message that is written by user */
> +static ssize_t ssif_bmc_write(struct file *file, const char __user *buf, size_t count,
> + loff_t *ppos)
> +{
> + struct ssif_bmc_ctx *ssif_bmc = to_ssif_bmc(file);
> + struct ssif_msg msg;
> + unsigned long flags;
> + ssize_t ret;
> +
> + if (count > sizeof(struct ssif_msg))
> + return -EINVAL;
> +
> + if (copy_from_user(&msg, buf, count))
> + return -EFAULT;
> +
> + if (!msg.len || count < msg.len + 1)
> + return -EINVAL;
> +
> + spin_lock_irqsave(&ssif_bmc->lock, flags);
> + while (ssif_bmc->response_in_progress) {
> + spin_unlock_irqrestore(&ssif_bmc->lock, flags);
> + if (file->f_flags & O_NONBLOCK)
> + return -EAGAIN;
> + ret = wait_event_interruptible(ssif_bmc->wait_queue,
> + !ssif_bmc->response_in_progress);
> + if (ret)
> + return ret;
> + spin_lock_irqsave(&ssif_bmc->lock, flags);
> + }
> +
> + /*
> + * The write must complete before the response timeout fired, otherwise
> + * the response is aborted and wait for next request
> + * Return -EINVAL if the response is aborted
> + */
> + ret = (ssif_bmc->response_timer_inited) ? 0 : -EINVAL;
> + if (ret)
> + goto exit;
> +
> + del_timer(&ssif_bmc->response_timer);
> + ssif_bmc->response_timer_inited = false;
> +
> + memcpy(&ssif_bmc->response, &msg, count);
> + ssif_bmc->is_singlepart_read = (msg.len <= MAX_PAYLOAD_PER_TRANSACTION);
> +
> + ssif_bmc->response_in_progress = true;
> +
> + /* ssif_bmc not busy */
> + ssif_bmc->busy = false;
> +
> + /* Clean old request buffer */
> + memset(&ssif_bmc->request, 0, sizeof(struct ssif_msg));
> +exit:
> + spin_unlock_irqrestore(&ssif_bmc->lock, flags);
> +
> + return (ret < 0) ? ret : count;
> +}
> +
> +static int ssif_bmc_open(struct inode *inode, struct file *file)
> +{
> + struct ssif_bmc_ctx *ssif_bmc = to_ssif_bmc(file);
> + int ret = 0;
> +
> + spin_lock_irq(&ssif_bmc->lock);
> + if (!ssif_bmc->running)
> + ssif_bmc->running = 1;
> + else
> + ret = -EBUSY;
> + spin_unlock_irq(&ssif_bmc->lock);
> +
> + return ret;
> +}
> +
> +static __poll_t ssif_bmc_poll(struct file *file, poll_table *wait)
> +{
> + struct ssif_bmc_ctx *ssif_bmc = to_ssif_bmc(file);
> + __poll_t mask = 0;
> +
> + poll_wait(file, &ssif_bmc->wait_queue, wait);
> +
> + spin_lock_irq(&ssif_bmc->lock);
> + /* The request is available, userspace application can get the request */
> + if (ssif_bmc->request_available)
> + mask |= POLLIN;
> +
> + spin_unlock_irq(&ssif_bmc->lock);
> +
> + return mask;
> +}
> +
> +static int ssif_bmc_release(struct inode *inode, struct file *file)
> +{
> + struct ssif_bmc_ctx *ssif_bmc = to_ssif_bmc(file);
> +
> + spin_lock_irq(&ssif_bmc->lock);
> + ssif_bmc->running = 0;
> + spin_unlock_irq(&ssif_bmc->lock);
> +
> + return 0;
> +}
> +
> +/*
> + * System calls to device interface for user apps
> + */
> +static const struct file_operations ssif_bmc_fops = {
> + .owner = THIS_MODULE,
> + .open = ssif_bmc_open,
> + .read = ssif_bmc_read,
> + .write = ssif_bmc_write,
> + .release = ssif_bmc_release,
> + .poll = ssif_bmc_poll,
> +};
> +
> +/* Called with ssif_bmc->lock held. */
> +static void complete_response(struct ssif_bmc_ctx *ssif_bmc)
> +{
> + /* Invalidate response in buffer to denote it having been sent. */
> + ssif_bmc->response.len = 0;
> + ssif_bmc->response_in_progress = false;
> + ssif_bmc->nbytes_processed = 0;
> + ssif_bmc->remain_len = 0;
> + ssif_bmc->busy = false;
> + memset(&ssif_bmc->part_buf, 0, sizeof(struct ssif_part_buffer));
> + wake_up_all(&ssif_bmc->wait_queue);
> +}
> +
> +static void response_timeout(struct timer_list *t)
> +{
> + struct ssif_bmc_ctx *ssif_bmc = from_timer(ssif_bmc, t, response_timer);
> + unsigned long flags;
> +
> + spin_lock_irqsave(&ssif_bmc->lock, flags);
> +
> + /* Do nothing if the response is in progress */
> + if (!ssif_bmc->response_in_progress) {
> + /* Recover ssif_bmc from busy */
> + ssif_bmc->busy = false;
> + ssif_bmc->response_timer_inited = false;
> + /* Set aborting flag */
> + ssif_bmc->aborting = true;
> + }
> +
> + spin_unlock_irqrestore(&ssif_bmc->lock, flags);
> +}
> +
> +/* Called with ssif_bmc->lock held. */
> +static void handle_request(struct ssif_bmc_ctx *ssif_bmc)
> +{
> + /* set ssif_bmc to busy waiting for response */
> + ssif_bmc->busy = true;
> + /* Request message is available to process */
> + ssif_bmc->request_available = true;
> + /* Clean old response buffer */
> + memset(&ssif_bmc->response, 0, sizeof(struct ssif_msg));
> + /* This is the new READ request.*/
> + wake_up_all(&ssif_bmc->wait_queue);
> +
> + /* Armed timer to recover slave from busy state in case of no response */
> + if (!ssif_bmc->response_timer_inited) {
> + timer_setup(&ssif_bmc->response_timer, response_timeout, 0);
> + ssif_bmc->response_timer_inited = true;
> + }
> + mod_timer(&ssif_bmc->response_timer, jiffies + msecs_to_jiffies(RESPONSE_TIMEOUT));
> +}
> +
> +static void calculate_response_part_pec(struct ssif_part_buffer *part)
> +{
> + u8 addr = part->address;
> +
> + /* PEC - Start Read Address */
> + part->pec = i2c_smbus_pec(0, &addr, 1);
> + /* PEC - SSIF Command */
> + part->pec = i2c_smbus_pec(part->pec, &part->smbus_cmd, 1);
> + /* PEC - Restart Write Address */
> + addr = addr | 0x01;
> + part->pec = i2c_smbus_pec(part->pec, &addr, 1);
> + part->pec = i2c_smbus_pec(part->pec, &part->length, 1);
> + if (part->length)
> + part->pec = i2c_smbus_pec(part->pec, part->payload, part->length);
> +}
> +
> +static void set_singlepart_response_buffer(struct ssif_bmc_ctx *ssif_bmc)
> +{
> + struct ssif_part_buffer *part = &ssif_bmc->part_buf;
> +
> + part->address = GET_8BIT_ADDR(ssif_bmc->client->addr);
> + part->length = ssif_bmc->response.len;
> +
> + /* Clear the rest to 0 */
> + memset(part->payload + part->length, 0, MAX_PAYLOAD_PER_TRANSACTION - part->length);
> + memcpy(&part->payload[0], &ssif_bmc->response.payload[0], part->length);
> +}
> +
> +static void set_multipart_response_buffer(struct ssif_bmc_ctx *ssif_bmc)
> +{
> + struct ssif_part_buffer *part = &ssif_bmc->part_buf;
> + u8 part_len = 0;
> +
> + part->address = GET_8BIT_ADDR(ssif_bmc->client->addr);
> + switch (part->smbus_cmd) {
> + case SSIF_IPMI_MULTIPART_READ_START:
> + /*
> + * Read Start length is 32 bytes.
> + * Read Start transfer first 30 bytes of IPMI response
> + * and 2 special code 0x00, 0x01.
> + */
> + ssif_bmc->nbytes_processed = 0;
> + ssif_bmc->block_num = 0;
> + part->length = MAX_PAYLOAD_PER_TRANSACTION;
> + part_len = MAX_IPMI_DATA_PER_START_TRANSACTION;
> + ssif_bmc->remain_len = ssif_bmc->response.len - part_len;
> +
> + part->payload[0] = 0x00; /* Start Flag */
> + part->payload[1] = 0x01; /* Start Flag */
> +
> + memcpy(&part->payload[2], &ssif_bmc->response.payload[0], part_len);
> + break;
> +
> + case SSIF_IPMI_MULTIPART_READ_MIDDLE:
> + /*
> + * IPMI READ Middle or READ End messages can carry up to 31 bytes
> + * IPMI data plus block number byte.
> + */
> + if (ssif_bmc->remain_len < MAX_IPMI_DATA_PER_MIDDLE_TRANSACTION) {
> + /*
> + * This is READ End message
> + * Return length is the remaining response data length
> + * plus block number
> + * Block number 0xFF is to indicate this is last message
> + *
> + */
> + /* Clean the buffer */
> + memset(&part->payload[0], 0, MAX_PAYLOAD_PER_TRANSACTION);
> + part->length = ssif_bmc->remain_len + 1;
> + part_len = ssif_bmc->remain_len;
> + ssif_bmc->block_num = 0xFF;
> + part->payload[0] = ssif_bmc->block_num;
> + } else {
> + /*
> + * This is READ Middle message
> + * Response length is the maximum SMBUS transfer length
> + * Block number byte is incremented
> + * Return length is maximum SMBUS transfer length
> + */
> + part->length = MAX_PAYLOAD_PER_TRANSACTION;
> + part_len = MAX_IPMI_DATA_PER_MIDDLE_TRANSACTION;
> + part->payload[0] = ssif_bmc->block_num;
> + ssif_bmc->block_num++;
> + }
> +
> + ssif_bmc->remain_len -= part_len;
> + memcpy(&part->payload[1], ssif_bmc->response.payload + ssif_bmc->nbytes_processed,
> + part_len);
> + break;
> +
> + default:
> + /* Do not expect to go to this case */
> + dev_err(&ssif_bmc->client->dev, "%s: Unexpected SMBus command 0x%x\n",
> + __func__, part->smbus_cmd);
> + break;
> + }
> +
> + ssif_bmc->nbytes_processed += part_len;
> +}
> +
> +static bool supported_read_cmd(u8 cmd)
> +{
> + if (cmd == SSIF_IPMI_SINGLEPART_READ ||
> + cmd == SSIF_IPMI_MULTIPART_READ_START ||
> + cmd == SSIF_IPMI_MULTIPART_READ_MIDDLE)
> + return true;
> +
> + return false;
> +}
> +
> +static bool supported_write_cmd(u8 cmd)
> +{
> + if (cmd == SSIF_IPMI_SINGLEPART_WRITE ||
> + cmd == SSIF_IPMI_MULTIPART_WRITE_START ||
> + cmd == SSIF_IPMI_MULTIPART_WRITE_MIDDLE ||
> + cmd == SSIF_IPMI_MULTIPART_WRITE_END)
> + return true;
> +
> + return false;
> +}
> +
> +/* Process the IPMI response that will be read by master */
> +static void handle_read_processed(struct ssif_bmc_ctx *ssif_bmc, u8 *val)
> +{
> + struct ssif_part_buffer *part = &ssif_bmc->part_buf;
> +
> + /* msg_idx start from 0 */
> + if (part->index < part->length)
> + *val = part->payload[part->index];
> + else if (part->index == part->length && ssif_bmc->pec_support)
> + *val = part->pec;
> + else
> + *val = 0;
> +
> + part->index++;
> +}
> +
> +static void handle_write_received(struct ssif_bmc_ctx *ssif_bmc, u8 *val)
> +{
> + /* msg_idx should not be 0 when reach here */
> + if (!ssif_bmc->msg_idx || ssif_bmc->msg_idx > MAX_TRANSACTION)
> + return;
> +
> + if (ssif_bmc->msg_idx == 1) {
> + ssif_bmc->part_buf.length = *val;
> + ssif_bmc->part_buf.index = 0;
> + } else {
> + ssif_bmc->part_buf.payload[ssif_bmc->part_buf.index++] = *val;
> + }
> +
> + ssif_bmc->msg_idx++;
> +}
> +
> +static bool validate_request_part(struct ssif_bmc_ctx *ssif_bmc)
> +{
> + struct ssif_part_buffer *part = &ssif_bmc->part_buf;
> + bool ret = true;
> + u8 cpec;
> + u8 addr;
> +
> + if (part->index == part->length) {
> + /* PEC is not included */
> + ssif_bmc->pec_support = false;
> + ret = true;
> + goto exit;
> + }
> +
> + if (part->index != part->length + 1) {
> + ret = false;
> + goto exit;
> + }
> +
> + /* PEC is included */
> + ssif_bmc->pec_support = true;
> + part->pec = part->payload[part->length];
> + addr = GET_8BIT_ADDR(ssif_bmc->client->addr);
> + cpec = i2c_smbus_pec(0, &addr, 1);
> + cpec = i2c_smbus_pec(cpec, &part->smbus_cmd, 1);
> + cpec = i2c_smbus_pec(cpec, &part->length, 1);
> + /*
> + * As SMBus specification does not allow the length
> + * (byte count) in the Write-Block protocol to be zero.
> + * Therefore, it is illegal to have the last Middle
> + * transaction in the sequence carry 32-byte and have
> + * a length of ‘0’ in the End transaction.
> + * But some users may try to use this way and we should
> + * prevent ssif_bmc driver broken in this case.
> + */
> + if (part->length)
> + cpec = i2c_smbus_pec(cpec, part->payload, part->length);
> +
> + if (cpec != part->pec)
> + ret = false;
> +
> +exit:
> + return ret;
> +}
> +
> +static void process_request_part(struct ssif_bmc_ctx *ssif_bmc)
> +{
> + struct ssif_part_buffer *part = &ssif_bmc->part_buf;
> +
> + switch (part->smbus_cmd) {
> + case SSIF_IPMI_SINGLEPART_WRITE:
> + /* save the whole part to request*/
> + ssif_bmc->request.len = part->length;
> + memcpy(ssif_bmc->request.payload, part->payload, part->length);
> +
> + break;
> + case SSIF_IPMI_MULTIPART_WRITE_START:
> + ssif_bmc->request.len = 0;
> +
> + fallthrough;
> + case SSIF_IPMI_MULTIPART_WRITE_MIDDLE:
> + case SSIF_IPMI_MULTIPART_WRITE_END:
> + /* Do the bound check here, not allow the request len exceed 254 bytes */
> + if (ssif_bmc->request.len <= MSG_PAYLOAD_LEN_MAX - part->length) {
> + memcpy(ssif_bmc->request.payload + ssif_bmc->request.len,
> + part->payload, part->length);
> + ssif_bmc->request.len += part->length;
> + } else {
> + dev_warn(&ssif_bmc->client->dev,
> + "Warn: Request exceeded 254 bytes, aborting");
> + /* Request too long, aborting */
> + ssif_bmc->aborting = true;
> + }
> + break;
> + default:
> + /* Do not expect to go to this case */
> + dev_err(&ssif_bmc->client->dev, "%s: Unexpected SMBus command 0x%x\n",
> + __func__, part->smbus_cmd);
> + break;
> + }
> +}
> +
> +static void process_smbus_cmd(struct ssif_bmc_ctx *ssif_bmc, u8 *val)
> +{
> + /* SMBUS command can vary (single or multi-part) */
> + ssif_bmc->part_buf.smbus_cmd = *val;
> + ssif_bmc->msg_idx = 1;
> +
> + if (*val == SSIF_IPMI_SINGLEPART_WRITE || *val == SSIF_IPMI_MULTIPART_WRITE_START) {
> + /*
> + * The response maybe not come in-time, causing host SSIF driver
> + * to timeout and resend a new request. In such case check for
> + * pending response and clear it
> + */
> + if (ssif_bmc->response_in_progress)
> + complete_response(ssif_bmc);
> +
> + /* This is new request, flip aborting flag if set */
> + if (ssif_bmc->aborting)
> + ssif_bmc->aborting = false;
> + }
> +}
> +
> +static void on_read_requested_event(struct ssif_bmc_ctx *ssif_bmc, u8 *val)
> +{
> + if (ssif_bmc->state == SSIF_READY ||
> + ssif_bmc->state == SSIF_START ||
> + ssif_bmc->state == SSIF_REQ_RECVING ||
> + ssif_bmc->state == SSIF_RES_SENDING) {
> + dev_warn(&ssif_bmc->client->dev,
> + "Warn: %s unexpected READ REQUESTED in state=%s\n",
> + __func__, state_to_string(ssif_bmc->state));
> + ssif_bmc->state = SSIF_ABORTING;
> + *val = 0;
> + return;
> +
> + } else if (ssif_bmc->state == SSIF_SMBUS_CMD) {
> + if (!supported_read_cmd(ssif_bmc->part_buf.smbus_cmd)) {
> + dev_warn(&ssif_bmc->client->dev, "Warn: Unknown SMBus read command=0x%x",
> + ssif_bmc->part_buf.smbus_cmd);
> + ssif_bmc->aborting = true;
> + }
> +
> + if (ssif_bmc->aborting)
> + ssif_bmc->state = SSIF_ABORTING;
> + else
> + ssif_bmc->state = SSIF_RES_SENDING;
> + }
> +
> + ssif_bmc->msg_idx = 0;
> +
> + /* Send 0 if there is nothing to send */
> + if (!ssif_bmc->response_in_progress || ssif_bmc->state == SSIF_ABORTING) {
> + *val = 0;
> + return;
> + }
> +
> + if (ssif_bmc->is_singlepart_read)
> + set_singlepart_response_buffer(ssif_bmc);
> + else
> + set_multipart_response_buffer(ssif_bmc);
> +
> + calculate_response_part_pec(&ssif_bmc->part_buf);
> + ssif_bmc->part_buf.index = 0;
> + *val = ssif_bmc->part_buf.length;
> +}
> +
> +static void on_read_processed_event(struct ssif_bmc_ctx *ssif_bmc, u8 *val)
> +{
> + if (ssif_bmc->state == SSIF_READY ||
> + ssif_bmc->state == SSIF_START ||
> + ssif_bmc->state == SSIF_REQ_RECVING ||
> + ssif_bmc->state == SSIF_SMBUS_CMD) {
> + dev_warn(&ssif_bmc->client->dev,
> + "Warn: %s unexpected READ PROCESSED in state=%s\n",
> + __func__, state_to_string(ssif_bmc->state));
> + ssif_bmc->state = SSIF_ABORTING;
> + *val = 0;
> + return;
> + }
> +
> + /* Send 0 if there is nothing to send */
> + if (!ssif_bmc->response_in_progress || ssif_bmc->state == SSIF_ABORTING) {
> + *val = 0;
> + return;
> + }
> +
> + handle_read_processed(ssif_bmc, val);
> +}
> +
> +static void on_write_requested_event(struct ssif_bmc_ctx *ssif_bmc, u8 *val)
> +{
> + if (ssif_bmc->state == SSIF_READY || ssif_bmc->state == SSIF_SMBUS_CMD) {
> + ssif_bmc->state = SSIF_START;
> +
> + } else if (ssif_bmc->state == SSIF_START ||
> + ssif_bmc->state == SSIF_REQ_RECVING ||
> + ssif_bmc->state == SSIF_RES_SENDING) {
> + dev_warn(&ssif_bmc->client->dev,
> + "Warn: %s unexpected WRITE REQUEST in state=%s\n",
> + __func__, state_to_string(ssif_bmc->state));
> + ssif_bmc->state = SSIF_ABORTING;
> + return;
> + }
> +
> + ssif_bmc->msg_idx = 0;
> + ssif_bmc->part_buf.address = *val;
> +}
> +
> +static void on_write_received_event(struct ssif_bmc_ctx *ssif_bmc, u8 *val)
> +{
> + if (ssif_bmc->state == SSIF_READY ||
> + ssif_bmc->state == SSIF_RES_SENDING) {
> + dev_warn(&ssif_bmc->client->dev,
> + "Warn: %s unexpected WRITE RECEIVED in state=%s\n",
> + __func__, state_to_string(ssif_bmc->state));
> + ssif_bmc->state = SSIF_ABORTING;
> +
> + } else if (ssif_bmc->state == SSIF_START) {
> + ssif_bmc->state = SSIF_SMBUS_CMD;
> +
> + } else if (ssif_bmc->state == SSIF_SMBUS_CMD) {
> + if (!supported_write_cmd(ssif_bmc->part_buf.smbus_cmd)) {
> + dev_warn(&ssif_bmc->client->dev, "Warn: Unknown SMBus write command=0x%x",
> + ssif_bmc->part_buf.smbus_cmd);
> + ssif_bmc->aborting = true;
> + }
> +
> + if (ssif_bmc->aborting)
> + ssif_bmc->state = SSIF_ABORTING;
> + else
> + ssif_bmc->state = SSIF_REQ_RECVING;
> + }
> +
> + /* This is response sending state */
> + if (ssif_bmc->state == SSIF_REQ_RECVING)
> + handle_write_received(ssif_bmc, val);
> + else if (ssif_bmc->state == SSIF_SMBUS_CMD)
> + process_smbus_cmd(ssif_bmc, val);
> +}
> +
> +static void on_stop_event(struct ssif_bmc_ctx *ssif_bmc, u8 *val)
> +{
> + if (ssif_bmc->state == SSIF_READY ||
> + ssif_bmc->state == SSIF_START ||
> + ssif_bmc->state == SSIF_SMBUS_CMD ||
> + ssif_bmc->state == SSIF_ABORTING) {
> + dev_warn(&ssif_bmc->client->dev,
> + "Warn: %s unexpected SLAVE STOP in state=%s\n",
> + __func__, state_to_string(ssif_bmc->state));
> + ssif_bmc->state = SSIF_READY;
> +
> + } else if (ssif_bmc->state == SSIF_REQ_RECVING) {
> + if (validate_request_part(ssif_bmc)) {
> + process_request_part(ssif_bmc);
> + if (ssif_bmc->part_buf.smbus_cmd == SSIF_IPMI_SINGLEPART_WRITE ||
> + ssif_bmc->part_buf.smbus_cmd == SSIF_IPMI_MULTIPART_WRITE_END)
> + handle_request(ssif_bmc);
> + ssif_bmc->state = SSIF_READY;
> + } else {
> + /*
> + * A BMC that receives an invalid request drop the data for the write
> + * transaction and any further transactions (read or write) until
> + * the next valid read or write Start transaction is received
> + */
> + dev_err(&ssif_bmc->client->dev, "Error: invalid pec\n");
> + ssif_bmc->aborting = true;
> + }
> + } else if (ssif_bmc->state == SSIF_RES_SENDING) {
> + if (ssif_bmc->is_singlepart_read || ssif_bmc->block_num == 0xFF)
> + /* Invalidate response buffer to denote it is sent */
> + complete_response(ssif_bmc);
> + ssif_bmc->state = SSIF_READY;
> + }
> +
> + /* Reset message index */
> + ssif_bmc->msg_idx = 0;
> +}
> +
> +/*
> + * Callback function to handle I2C slave events
> + */
> +static int ssif_bmc_cb(struct i2c_client *client, enum i2c_slave_event event, u8 *val)
> +{
> + unsigned long flags;
> + struct ssif_bmc_ctx *ssif_bmc = i2c_get_clientdata(client);
> + int ret = 0;
> +
> + spin_lock_irqsave(&ssif_bmc->lock, flags);
> +
> + switch (event) {
> + case I2C_SLAVE_READ_REQUESTED:
> + on_read_requested_event(ssif_bmc, val);
> + break;
> +
> + case I2C_SLAVE_WRITE_REQUESTED:
> + on_write_requested_event(ssif_bmc, val);
> + break;
> +
> + case I2C_SLAVE_READ_PROCESSED:
> + on_read_processed_event(ssif_bmc, val);
> + break;
> +
> + case I2C_SLAVE_WRITE_RECEIVED:
> + on_write_received_event(ssif_bmc, val);
> + break;
> +
> + case I2C_SLAVE_STOP:
> + on_stop_event(ssif_bmc, val);
> + break;
> +
> + default:
> + dev_warn(&ssif_bmc->client->dev, "Warn: Unknown i2c slave event\n");
> + break;
> + }
> +
> + if (!ssif_bmc->aborting && ssif_bmc->busy)
> + ret = -EBUSY;
> +
> + spin_unlock_irqrestore(&ssif_bmc->lock, flags);
> +
> + return ret;
> +}
> +
> +static int ssif_bmc_probe(struct i2c_client *client, const struct i2c_device_id *id)
> +{
> + struct ssif_bmc_ctx *ssif_bmc;
> + int ret;
> +
> + ssif_bmc = devm_kzalloc(&client->dev, sizeof(*ssif_bmc), GFP_KERNEL);
> + if (!ssif_bmc)
> + return -ENOMEM;
> +
> + spin_lock_init(&ssif_bmc->lock);
> +
> + init_waitqueue_head(&ssif_bmc->wait_queue);
> + ssif_bmc->request_available = false;
> + ssif_bmc->response_in_progress = false;
> + ssif_bmc->busy = false;
> + ssif_bmc->response_timer_inited = false;
> +
> + /* Register misc device interface */
> + ssif_bmc->miscdev.minor = MISC_DYNAMIC_MINOR;
> + ssif_bmc->miscdev.name = DEVICE_NAME;
> + ssif_bmc->miscdev.fops = &ssif_bmc_fops;
> + ssif_bmc->miscdev.parent = &client->dev;
> + ret = misc_register(&ssif_bmc->miscdev);
> + if (ret)
> + goto out;
> +
> + ssif_bmc->client = client;
> + ssif_bmc->client->flags |= I2C_CLIENT_SLAVE;
> +
> + /* Register I2C slave */
> + i2c_set_clientdata(client, ssif_bmc);
> + ret = i2c_slave_register(client, ssif_bmc_cb);
> + if (ret) {
> + misc_deregister(&ssif_bmc->miscdev);
> + goto out;
> + }
> +
> + return 0;
> +out:
> + devm_kfree(&client->dev, ssif_bmc);
> + return ret;
> +}
> +
> +static int ssif_bmc_remove(struct i2c_client *client)
> +{
> + struct ssif_bmc_ctx *ssif_bmc = i2c_get_clientdata(client);
> +
> + i2c_slave_unregister(client);
> + misc_deregister(&ssif_bmc->miscdev);
> +
> + return 0;
> +}
> +
> +static const struct of_device_id ssif_bmc_match[] = {
> + { .compatible = "ssif-bmc" },
> + { },
> +};
> +MODULE_DEVICE_TABLE(of, ssif_bmc_match);
> +
> +static const struct i2c_device_id ssif_bmc_id[] = {
> + { DEVICE_NAME, 0 },
> + { },
> +};
> +MODULE_DEVICE_TABLE(i2c, ssif_bmc_id);
> +
> +static struct i2c_driver ssif_bmc_driver = {
> + .driver = {
> + .name = DEVICE_NAME,
> + .of_match_table = ssif_bmc_match,
> + },
> + .probe = ssif_bmc_probe,
> + .remove = ssif_bmc_remove,
> + .id_table = ssif_bmc_id,
> +};
> +
> +module_i2c_driver(ssif_bmc_driver);
> +
> +MODULE_AUTHOR("Quan Nguyen <quan@...amperecomputing.com>");
> +MODULE_AUTHOR("Chuong Tran <chuong@...amperecomputing.com>");
> +MODULE_DESCRIPTION("Linux device driver of the BMC IPMI SSIF interface.");
> +MODULE_LICENSE("GPL");
> diff --git a/drivers/char/ipmi/ssif_bmc.h b/drivers/char/ipmi/ssif_bmc.h
> new file mode 100644
> index 000000000000..2c3fc2a4698f
> --- /dev/null
> +++ b/drivers/char/ipmi/ssif_bmc.h
> @@ -0,0 +1,107 @@
> +/* SPDX-License-Identifier: GPL-2.0+ */
> +/*
> + * The driver for BMC side of SSIF interface
> + *
> + * Copyright (c) 2022, Ampere Computing LLC
> + *
> + */
> +#ifndef __SSIF_BMC_H__
> +#define __SSIF_BMC_H__
> +
> +#define DEVICE_NAME "ipmi-ssif-host"
> +
> +#define GET_8BIT_ADDR(addr_7bit) (((addr_7bit) << 1) & 0xff)
> +
> +/* A standard SMBus Transaction is limited to 32 data bytes */
> +#define MAX_PAYLOAD_PER_TRANSACTION 32
> +/* Transaction includes the address, the command, the length and the PEC byte */
> +#define MAX_TRANSACTION (MAX_PAYLOAD_PER_TRANSACTION + 4)
> +
> +#define MAX_IPMI_DATA_PER_START_TRANSACTION 30
> +#define MAX_IPMI_DATA_PER_MIDDLE_TRANSACTION 31
> +
> +#define SSIF_IPMI_SINGLEPART_WRITE 0x2
> +#define SSIF_IPMI_SINGLEPART_READ 0x3
> +#define SSIF_IPMI_MULTIPART_WRITE_START 0x6
> +#define SSIF_IPMI_MULTIPART_WRITE_MIDDLE 0x7
> +#define SSIF_IPMI_MULTIPART_WRITE_END 0x8
> +#define SSIF_IPMI_MULTIPART_READ_START 0x3
> +#define SSIF_IPMI_MULTIPART_READ_MIDDLE 0x9
> +
> +/* Include netfn and cmd field */
> +#define MSG_PAYLOAD_LEN_MAX 254
> +/*
> + * IPMI 2.0 Spec, section 12.7 SSIF Timing,
> + * Request-to-Response Time is T6max(250ms) - T1max(20ms) - 3ms = 227ms
> + * Recover ssif_bmc from busy state if it takes up to 500ms
> + */
> +#define RESPONSE_TIMEOUT 500 /* ms */
> +
> +struct ssif_msg {
> + u8 len;
> + u8 payload[MSG_PAYLOAD_LEN_MAX];
> +} __packed;
> +
> +struct ssif_part_buffer {
> + u8 address;
> + u8 smbus_cmd;
> + u8 length;
> + u8 payload[MAX_PAYLOAD_PER_TRANSACTION];
> + u8 pec;
> + u8 index;
> +} __packed;
> +
> +/*
> + * SSIF internal states:
> + * SSIF_READY 0x00 : Ready state
> + * SSIF_START 0x01 : Start smbus transaction
> + * SSIF_SMBUS_CMD 0x02 : Received SMBus command
> + * SSIF_REQ_RECVING 0x03 : Receiving request
> + * SSIF_RES_SENDING 0x04 : Sending response
> + * SSIF_BAD_SMBUS 0x05 : Bad SMbus transaction
> + */
> +enum ssif_state {
> + SSIF_READY,
> + SSIF_START,
> + SSIF_SMBUS_CMD,
> + SSIF_REQ_RECVING,
> + SSIF_RES_SENDING,
> + SSIF_ABORTING,
> + SSIF_STATE_MAX
> +};
> +
> +struct ssif_bmc_ctx {
> + struct i2c_client *client;
> + struct miscdevice miscdev;
> + int msg_idx;
> + bool pec_support;
> + /* ssif bmc spinlock */
> + spinlock_t lock;
> + wait_queue_head_t wait_queue;
> + u8 running;
> + enum ssif_state state;
> + /* Timeout waiting for response */
> + struct timer_list response_timer;
> + bool response_timer_inited;
> + /* Flag to identify a Multi-part Read Transaction */
> + bool is_singlepart_read;
> + u8 nbytes_processed;
> + u8 remain_len;
> + u8 recv_len;
> + /* Block Number of a Multi-part Read Transaction */
> + u8 block_num;
> + bool request_available;
> + bool response_in_progress;
> + bool busy;
> + bool aborting;
> + /* Buffer for SSIF Transaction part*/
> + struct ssif_part_buffer part_buf;
> + struct ssif_msg response;
> + struct ssif_msg request;
> +};
> +
> +static inline struct ssif_bmc_ctx *to_ssif_bmc(struct file *file)
> +{
> + return container_of(file->private_data, struct ssif_bmc_ctx, miscdev);
> +}
> +#endif /* __SSIF_BMC_H__ */
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